Skateboards are commonly used for recreation purposes. Typical skateboards comprise an elongated board supported on four wheels. The board is arranged above the wheels. The skateboard rider balances on the board and adjusts the direction of travel by adjusting the pressure of his weight at various locations on the board.
As the board is located above the wheels, the wheel diameter is limited due to the necessity of the rider balancing on the board above the wheels and to allow the rider to adjust direction of travel by imparting pressure variations on the board. skateboard is therefore limited to relatively smooth terrain due to the need to accommodate relative small wheel size.
Skateboards are conventionally constructed with a pair of trucks attached to the underside of the elongated board. The trucks are aligned along the center line of the board. One truck is located near the front of the board with the other truck located near the end. Each truck supports a pair of skateboard wheels, the skateboard wheels extending laterally outward from each other and supported on axles. The trucks are typically screwed or otherwise fastened to the underside of the skateboard.
In a typical skateboard an axle support is mounted on the truck. An axle extends laterally outward from either side of the axle support. The skateboard wheels are each independently rotatable about the axle.
The axle is typically rotatable about a downward extending post, the post located adjacent the axle and towards the longitudinal center of the skateboard. A pivot pin extends from the axle member upwardly and outwardly from the center of the skateboard. The pivot pin engages a socket contained on the truck. Resilient bearings are provided at the engagement of the pivot pin with the socket. Resilient bearings are also provided at the engagement of the axle with the downward extending post. The resilient bearings allow limited rotation of the axle in both the horizontal and vertical plane.
The skateboard rider shifts weight on the skateboard to adjust the direction of travel of the skateboard. Shifting of weight by the rider towards a lateral side of the skateboard increases downward pressure on the wheels of such side. The axle is inclined slightly downward on the side to which weight is applied and lifted at the opposite side. This creates an increased drag on the forward rotation of the wheels, while at the same time decreasing pressure between the wheels and the ground on the opposite side of the skateboard. The foregoing effects turning of the skateboard in the direction of the side to which the weight is shifted.
An important aspect of a conventional skateboard is the ability of the rider to assert pressure on the wheel-to-ground contact interface to effectively control turning movements of the skateboard.
Conventional skateboards are normally limited in use to sidewalks, streets and other relatively smooth surfaces. It is a significant disadvantage of current skateboards that they cannot be operated on slightly irregular terrains such as grassy areas or dirt tracks. A skateboard-like apparatus utilizing larger wheels would be adaptable to more irregular terrain as a larger wheel diameter could overcome more obstacles. In particular, a skateboard-like apparatus utilizing larger wheels with relatively flexible tires, such as pneumatic wheels, would be adaptable to more irregular terrain as the inflated pneumatic wheels would enhance performance in a slightly irregular terrain.
Rosenblum U.S. Pat. No. 4,133,546 discloses a coasting vehicle adapted to be steered. The vehicle includes a pair of parallel platforms adapted to rotate or tilt about parallel axes, the platforms being coupled together. Wheels are mounted exterior of the platform fore and aft thereof. By having the wheels outboard of the coupled platforms they can be made larger so that the vehicle may be operated on other-than-paved surfaces. The Rosenblum patent discloses platform planes below the rolling axes of the wheels. Steering means are provided whereby the wheels may be steered by lateral movement of a track rod responsive to pivoting of the parallel platforms. The Rosenblum disclosure teaches the use of ski boots and ski bindings to practice the invention.
Johnson U.S. Pat. No. 4,185,847 discloses a skateboard having wheels mounted in independent suspension. Other patents describing skateboard or roller skateboard wheel mounting assemblies include Amelio U.S. Pat. No. 3,992,025, Kunselman U.S. Pat. No. 3,436,088, Mongeon U.S. Pat. No. 4,402,521 and Owsen, et. al. U.S. Pat. No. 2,676,812.
It is an object of the present invention to provide a coaster board operable on smooth or paved surfaces and readily operable on slightly irregular surfaces such as grassy areas, dirt tracks and other surfaces.
It is a further object of the present invention to provide a coaster board which may be steered by shifting of the body weight of the coaster board rider.
These and other objects of the present invention are accomplished with a coaster board operable on irregular terrain. The coaster board includes a longitudinally elongated platform supported on a pair of spaced suspension and steering systems. Each suspension and steering system includes a suspension rod and a cooperative steering bar. Each suspension rod is resiliently attached to the underside of the platform near the lateral center of the platform. Each suspension rod is supported on an axle and a pair of independently rotatable wheels mounted on the axle laterally exterior of the platform. Each suspension rod includes an orifice disposed laterally centrally of the suspension rod. A steering bar includes aligned distal ends attached to the bottom surface of the platform. Each steering bar end is laterally exterior of the location of the suspension rod connection to the platform. A central bar segment extends downwardly from the platform through the suspension rod orifice and engages the interior lateral sides of the orifice whereby rotation of the coaster board platform and the steering bar in a vertical plane about the longitudinal axis of the platform exerts downward pressure on a side of the suspension rod.